Elizabeth is right, if the cable you are using is causing a problem, it could be from capacitance it is adding to your preamps output. This effect is the same as adding a capacitor to "roll off" the top frequencies. This occurs only if the measured PF ( picofarads ) total is sufficiently high. I looked for specifications at the Monster Cable web site before posting here. Their advise simply says not to run more than 30 feet. They do not post technical specifications such as the PF per foot measurement of any of their interconnects. If you could borrow something for demo from the Purist Audio line of interconnect, they have very low loss. The inexpensive end of their line ( Elementa) measures something like 17 PF per foot. Even driving a 49K amplifier load with an unbuffered output preamp, this would leave a single ended (RCA based) signal intact at even a 40 foot run.
